Conformational transitions in the Ca2+ + Mg2+-activated ATPase and the binding of Ca2+ ions
- 1 July 1986
- journal article
- research article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 237 (1) , 197-206
- https://doi.org/10.1042/bj2370197
Abstract
We have studied the fluorescence of the Ca2+ + Mg2+-activated ATPase of sarcoplasmic reticulum labelled with fluorescein isothiocyanate. The change in intensity of fluorescein fluorescence caused by addition of Ca2+ to the labelled ATPase can be interpreted in terms of a two-conformation model for the ATPase, one conformation (E1) having a high affinity for Ca2+, the other (E2) a low affinity. Effects of Ca2+ as a function of pH allow an estimate of the effect of pH on the E1/E2 ratio, consistent with kinetic studies. A model is presented for binding of Ca2+ to the ATPase as a function of pH that is consistent both with the data on the E1/E2 equilibrium and with literature data on Ca2+ binding.This publication has 36 references indexed in Scilit:
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